VBA Daniel used the nested loop

This is a free tutorial 《Excel VBA： Office automation 》 Of the 11 section , Introduce nested loop structure .

1. know VBA： What is? VBA？

2. These are mastered , You dare to say that you understand VBA

3.VBA Variable 5 Summary of the year's pits

4.VBA The most important mandatory statement in English is , Who can see who can understand

5.VBA Master the loop structure , You can improve your efficiency 500 times

6. Master VBA Branching structure , Write less programs 100 That's ok

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8.VBA String Introduction , This is enough

9. And write your own code ？VBA Record macro to learn about

10.VBA The circular structure is not good , Let's have another one

Read the previous series VBA Content , I think everyone must have found a problem ： All the previous actual cases are handled 「 One column, many lines 」 problem , But what we often encounter in practical work is 「 Multiple rows and columns 」 problem , How to deal with this problem ？

What I want to say is , This section of nested loop sharing is devoted to this problem .

1. What is loop nesting ？

So-called 「 A nested loop 」 Is to share what we shared earlier Branching structure 、 Loop structure And so on , Then complete complex tasks that are difficult for a single knowledge point to complete alone .

The popular explanation is ：IF loop and WHILE Loop everyone together . You have me , I have you. , Realize the actual needs of the work .

2. Loop nested case practice

Case study ： Will make use of 「1- Macro program 」 according to 「2- Hierarchy 」 The rules of , Yes 「3- Data area 」 Data processing , formation 「4- Output results 」.

First , We make a preliminary analysis of the needs of this case ：

“ utilize 「1- Macro program 」” Is to draw a rounded rectangle with a high color value , And then specify what we're going to write Macro program .

“ according to 「2- Hierarchy 」 The rules of ” According to the hierarchical structure conditions on the right , utilize IF Branching structure Judge the specified conditions .

“ Yes 「3- Data area 」 Data processing ” Is to choose what you are good at Loop structure , Cycle through the specified data areas one by one .

“ formation 「4- Output results 」” It is to output the results in the specified format at the specified location .

After analyzing the above requirements , We basically have a clear idea , Then move on .

Same as before , First , We show the code that has implemented the case function ; then , Explain the main structure of this code ; Last , Simulate the operation of the code , In order to deepen our understanding .

Through the code shown above , We can see that the core architecture of the whole code adopts 3 Hierarchical nested structure , Respectively ：

The first 1 Layer of Do...While Loop structure , It is mainly used to control tables 「 That's ok 」 A cycle of directions ;

The first 2 Layer of For Loop structure , It is mainly used to control tables 「 Column 」 A cycle of directions ;

The first 3 Layer of IF Branching structure , It is mainly used to judge the specified conditions .

adopt 3 The loop nesting structure formed by the combination of , Finally, the more complex of the above cases was completed 「 Multiple rows and columns 」 demand .

According to the code above , Let's simulate the running process of this little program

1） Before program reading 5 That's ok

The program uses 「 Compulsory declaration 」, Defined variables i And variables j, And the variable i Assign initial value as 3, And assignment variables i by 3 The main reason is ： Because of the variable i control 「 That's ok 」 A cycle of directions , The data area is judged from the 3 The line .

2） Program execution Do...While The loop body

Program read 「Do While Cells(i, 2) <> ""」 Indicates that the program has entered the 1 Layer of 「 Row cycle 」, In other words ： Cell B3 Whether the value of is empty ？ We found by looking at the left 「 Cell B3=738」, Not empty . then , The program goes to the next line to execute .

3） Program execution For Loop structure

Program read 「For j = 2 To 7」 Indicates that the program has entered the 2 Layer of 「 Column loop 」, In other words ：j The value is 2 To 7 Between , Every cycle j The value of is increased 1 , until j=7 When the whole For The loop ends .

See here , Maybe you have some questions , Why variable i To limit its value range ？

Everyone must have their own answers in their hearts ： The reason why the variable j The value of is limited to 2-7 Between , Because the data areas we need to judge are mainly distributed in B Column -G Column , Their corresponding cells The numerical value is 2-7.

4） Program execution IF Branching structure

At this point, the program enters If Branching structure , From the above, we can know that at this time ：i = 3,j = 2, namely ：「Cells(2, 3)」 Express 「 Cell B3」, By looking at the data on the left, you can see 「 Cell B3 = 738」, It is located in 「 Rich peasants 」 Range interval , Then it is obvious that only the second branch structure meets the above conditions , namely ： The program executes automatically 「ElseIf Cells(i, j) >= 500 And Cells(i, j) < 700 Then」 and 「Cells(i, j) = Cells(i, j) & " | Rich peasants "」.

And because according to the rules , Cells that meet the criteria , Will be in the specified format ——「 income | Grade 」 Write results , such as ：「738 | Local tyrants 」. therefore , Will appear 「Cells(i, j) = Cells(i, j) & " | Rich peasants "」 This code .

then , Wait until variable j After the execution, it is 2-7 After all values of the interval , Original table No 3 All the data of the row will be converted , Here's the picture ：

In other words, it means ： When 「i = 3」 when ,For The branch structure should be circular 1 Wheel variable j, For the original table, it completes the 3 Conversion of row data .

5） Program read 「i = i + 1」 and 「Loop」

When the program is executed to 「i = i + 1」 When , Indicates the last round of variables i The loop execution of has been completed ; And the program runs to 「Loop」 when , Indicates that the program is ready to execute the next round .

When the program conforms to 「Do While Cells(i, 2) <> ""」 This condition is , The program will proceed to the next round . Once the above conditions are not met , Then the whole program will jump out 「Do...While」 loop .

When 「i = 15」 when , here 「Cells(i, 2)」 Express 「 Cell B15」, Looking at the table on the left, you can find , Cell is empty , disqualification , Because there is no other code below , Get into 「End Sub」 sentence , End directly .

3. summary

Loop nesting is the branching structure we shared earlier 、 Loop structure, etc , Then complete complex tasks that are difficult for a single knowledge point to complete alone .

From the above, we can find that ： Loop nesting can be compared to Lego building blocks , Use different building blocks to combine different things . As for what to combine , It depends on your thinking 、 practice , Think again and practice again , So again and again .

We found that , In fact, many things in the world are composed of different small modules . So is knowledge , Only the continuous accumulation 、 Constant practice , And the rest will be left to time .